19th Century

German inventor Nicolaus Otto (1832-1891) is credited with creating the first successful four-stroke internal combustion engine. He also devised and built numerous other types of engines, including the Free-Piston engine.

did Otto have it right the first time?

One of the keys to higher engine efficiency is eliminating the crankshaft constraints on combustion.

Operating without these constraints, the free-piston engine has the potential of yielding higher efficiency then the crankshaft engine. Otto demonstrated that in 1867 and recent analysis has re-affirmed it.